An optical imaging device in which an outer mount and an inner ring which is adjustable relative to it are preferably fabricated monolithically from one piece is known from DE 199 01 295 A1. A manipulating device which serves to displace the optical element held in the inner ring in a path-controlled manner in direction perpendicular to the optical axis comprises between the inner ring and outer ring a system of circumferential slots with intermediate connection members, a rotary joint and at least one adjusting joint with an adjusting member.
The disadvantage of this solution consists particularly in that, as a result of the multitude of differently formed manipulator units, referred to therein as manipulator elements, it has a complicated and asymmetrical construction which is unsuitable for symmetrical systems or which leads to system instabilities.
A lens mount which is fashioned from one piece and, therefore, monolithically is also known from EP 1 577 693 A2. In a preferred construction, an inner ring is connected to an outer ring via three manipulator units, referred to therein as adjusting joints, with two articulated arms in each instance and an adjusting part located therebetween. Actuators act at the adjusting joints for lateral adjustment of the inner ring and, therefore, of the optical element. The two articulated arms and the adjusting part located therebetween can also be conceived of as two toggle levers which are connected in parallel and formed in each instance from two levers (members) connected via a joint, one of the free lever ends is connected in each instance to the lens mount via a joint and the other respective free ends are rigidly connected to one another via the adjusting part. The two joints connecting the lens mount to the manipulator units are arranged radially one behind the other. As a result of the two toggle levers arranged one behind the other in radial direction in a plane, the manipulator units take up a relatively large space.
The solution shown here is characterized by a higher temperature stability compared to the above-cited DE 199 01 295 A1.
A lens mount according to the above-cited EP 1 577 693 A2 claims the advantage that a greater lateral stiffness of the inner ring connection can be achieved by making the articulated arms shorter so that the lens mount with the lens held therein is stiffer against natural vibrations. However, increasing lateral stiffness by shortening the articulated arms is accomplished at the expense of adjustment sensitivity which includes not only the length of the members but also the bending of the articulated arms.
In this case, however, the length of the articulated arms is further predetermined by the permissible material loading; that is, if the permissible material loading is reached with predetermined actuating displacement and predetermined sensitivity, a further shortening of the joints to increase stiffness or natural frequency is not possible. Consequently, two articulated arms which are relatively thin and also long in proportion to cross section are always required in order to carry out the function as adjusting unit or joint, which basically limits the achievable lateral and axial stiffness.
DE 10 2007 030 579 A1 describes a first construction for a laterally adjustable lens mount such as that corresponding substantially to the above-cited EP 1 577 693 A2, i.e., three manipulator units which are arranged at an offset of 120° relative to one another are formed in each instance as a member which transitions at its fixed end into two tangentially oriented articulated arms, referred to therein as webs, which are connected to the inner mount part and outer mount part, respectively.
In a second embodiment form, the webs connecting the member to the inner mount part and outer mount part are radially oriented so that a greater lateral stiffness is achieved.
However, with radial webs compared to the tangential webs, a deflection of the lever due to a radially acting force introduced at the free lever end via a manipulator leads to much higher tensile forces in the webs. In this case, the occurrence of unwanted stresses in the inner ring is unavoidable.
In both constructions, the manipulator units are simple lever linkages having a gear ratio which is determined via the length of the member and the bending of the webs in radial direction. To obtain a high sensitivity with corresponding actuating paths, the webs and articulated arms are constructed to be long, which can lead to twisting in axial direction.
A lens mount which is divided through material cuts in an annular ring into a stationary outer mount ring, a laterally adjustable inner mount ring and at least two connection structures which can be manipulated in each instance via a manipulator is known from DE 10 2008 029 161 B3, cited above. The connection structures are formed by two members which act as coupler and which are connected to one another and, in each instance, by an end to the inner mount ring and to the outer mount ring, respectively, via flexure bearings. The two members together form an angle greater than 90° and less than 180° so that the flexure bearing connecting the two members, considered tangentially, is arranged between the two members. In a preferred embodiment form, a lever is fixedly arranged at the member connected to the outer mount ring, the free end of this lever facing the flexure bearing formed at the inner mount ring.
To perform an adjustment of the inner mount ring relative to the outer mount ring, a radial force is directed to the free end of the lever via a manipulator which is temporarily inserted into the outer mount ring or is permanently arranged in the outer mount ring. A deflection of the lever brought about in this way is transformed into a lateral displacement of the flexure bearing connecting the connection structure to the inner mount ring. For this purpose, the lever should be as long as possible to achieve high sensitivity. At the same time it is desirable that the inner mount ring be constructed so as to be as stiff as possible against radially introduced forces, which can be achieved principally when the flexure bearing connecting the connection structure to the inner mount ring has the greatest possible radial distance from the axis of symmetry of the annular body.
A final adjustment by turning is usually carried out for lens mounts of this kind after the material slots have been introduced, e.g., through spark erosion or water jet cutting, and after a lens has been fitted to the inner mount ring. Since, in doing so, surfaces must be machined at the outer mount ring, free surfaces must be provided in the outer mount ring for receptacles which are needed for this purpose and via which the lens mounts can be received by a tool holder. Free surfaces of this kind may also be required for installing component parts remaining on the lens mount such as a shutter. The space requirement needed for this is taken into account in the dimensioning of the thickness of the outer mount ring (radial extension of the outer mount ring). The arrangement of free surfaces of this kind is not taken into consideration in the above-mentioned DE 10 2008 029 161 B3 or in other publications of the disclosed prior art.
It may be considered an ongoing challenge to construct a lens mount which is as small as possible with respect to its radial extension, but at the same time to construct an inner mount ring which is as large as possible with respect to its radial extension in order to achieve a high radial stiffness of the inner mount ring.
It is the object of the invention to improve a lens mount according to the above-cited DE 10 2008 029 161 B3 such that it has a greater lateral stiffness and a lower natural frequency.
This object is met for an adjustable lens mount which is divided through material cuts in an annular body with an axis of symmetry into an outer mount ring, a laterally adjustable inner mount ring and at least two connection structures. The at least two connection structures communicate in each instance with a manipulator with a radial acting axis. They have in each instance a coupling member which is connected to the inner mount ring via a first flexure bearing at a first coupling end and a lever with a free first lever end against which one of the manipulators abuts. The lever communicates by a second lever end with a second coupling end of the coupling member via a second flexure bearing and is connected between a free first lever end and a second lever end to the outer mount ring via a third flexure bearing. The first flexure bearing is arranged farther outside radially than the third flexure bearing. The coupling member, abstracted to a first straight connecting line, and the lever, abstracted to a second connecting line, are arranged opposite one another with reference to an imaginary radial straight line passing through the second flexure bearing, the coupling member forms a first angle of less than 90° with the imaginary radial straight line, and the lever forms a second angle of less than 90° with the imaginary radial straight line.
In an advantageous manner, the first angle formed by the coupling member with the imaginary radial straight line is less than 45°, particularly less than 30°, so that the first flexure bearing lies far outside radially and the coupling member is kept short.
It turns out to be favorable when the second angle formed by the lever with the imaginary radial straight line is greater than 45° so that a length of the lever of one of the connection structure scan be elongated until approximating an adjacent one of the connection structures so that the sensitivity of the adjustment can be widely varied via the choice of the length of the lever.
As a result of the above-mentioned features of the connection structures, projections result radially outside of the second flexure bearing which are advantageously constructed in such a way that they are sufficient with respect to size and geometry to be utilized as free surfaces, e.g., for a receptacle in a tool holder.